The objective of this project is to assess the occurrence of early improvement within the first two weeks of antidepressant treatment and to correlate this improvement with favorable therapeutic outcome at the end of the acute and treatment continuation phases (8 and 24 weeks, respectively).

An ongoing debate, as long-running as treatment with antidepressants itself, is the delay in response to these drugs. Antidepressant drugs take 2 to 4 weeks to produce the treatment response effect (at least 50% improvement in depressive symptoms versus baseline levels). This delay in antidepressant response can prove highly problematic since, during this interim period, the patient is exposed to the suffering, debilitative effects, direct and indirect costs and risks associated with major depressive disorder (MDD).

Another important issue is when to define failure of a therapeutic trial and how to change treatment. Between 30 and 50% of MDD patients fail to respond to adequate first-line treatment. If favorable outcome is defined as full remission (as opposed to only 50% improvement) of the patient, the failure rate during first trial is greater still. Some reviews recommend dose adjustments every two weeks and a 4-8 week wait before treatment change for poor response. Despite these recommendations, the question over when and how to change treatment strategy warrants further debate.

Early improvement in antidepressant treatment is desirable because it reduces the suffering, losses and costs associated with MDD. In addition, the risk of suicidal ideation or committing suicide are reduced in patients presenting early improvement of depressive symptoms. However, early improvement not only reduces risk but also predicts outcome at the end of the acute phase of treatment. A number of studies investigating different antidepressants have shown that the presence of early response is a good predictor of favorable outcome at the end of the acute phase of treatment (after 6 or 8 weeks of treatment). A meta-analysis reviewing 41 simple or double-blind clinical trials included a total of 6562 patients.

Early improvement, defined as a 20% reduction in score on the Hamilton Depression Scale (HAMD-17) within 2 weeks, was associated with sustained response, remission (defined as HAM-D-17 score ≤7). While early response has been amply demonstrated in numerous clinical trials, there are gaps in knowledge on the subject. Scant studies have documented whether there are differences in the pattern of early improvement among different antidepressants. Similarly, there is a dearth of studies analyzing whether the presence or otherwise of early response has the same predictive value for different antidepressants. Another little explored aspect is the arbitrary nature of the criteria defining onset of improvement, early improvement, treatment response and symptomatological remission. Studies tend to reproduce previously-adopted criteria without elaborating on the exploratory analyses justifying the cut-off points adopted.

The aim of the present study is to assess the presence of early improvement after one and two weeks of treatment with sertraline. Besides assessing the presence of early response, the study will include an exploratory analysis assessing positive and negative predictive values, sensitivity and specificity of early improvement as a predictor of sustained response and remission after 6, 8 and 24 weeks of treatment.

Inclusion Criteria:

• Patients Presenting Depressive Episode according to DSM-IV-TR

Exclusion Criteria:

• Patients presenting: psychotic symptoms, Axis 1 comorbidities (except specific phobia, specific social phobia and nicotine dependence) or risk of suicide (defined as score = 3 on item 3 of the 17-item HAMD or at the discretion of rater);
• Other exclusion criteria are having a serious or unstable medical condition, including cardiovascular, hepatic, endocrinologic, neurological or renal conditions.
• Clinically significant abnormalities on laboratory or ECG exams or those which, in the investigator ́s opinion, indicate a serious medical issue, require a major intervention or may interfere in the antidepressant treatment, also constitute grounds for exclusion.